TROPICAL WEATHER FORECAST SYNOPSIS…AUG. 20, 2013…ISSUED 11:30 A.M. EDT…PHFC

Good day everyone!

Pretty much the same as yesterday, with only a couple of areas I’m sort of interested in.

First off, I’ll touch on the area of on and off thunderstorm activity near the Florida Keys.  This area is being enhanced by an upper level low to the NNE of the area, and by another south, in the Caribbean Sea.  There is no surface reflection of this, and is confirmed by buoy data from around the area, of steady pressures at the surface.

WATL SATELLITE LOOP

A small area of thunderstorm activity is still seen waxing and waning in the Caribbean, just south of, and between Hispaniola and Puerto Rico.  This is associated with a surface trof of low pressure moving toward the west.  At the moment, this area is undergoing 30 knots of westerly shear.  Although I am not expecting development during the next 48 hours, vorticity is currently present at 925 mb and 850 mb.  So for giggles and grins, I will continue to monitor this area as it moves toward the west, for any significant changes in the pattern.

925 MB VORTICITY MAP

850 MB VORTICITY MAP

Elsewhere, and area of showers and thunderstorms near 7.0N…34.0W remains disorganized.  This area is associated with a 1010 mb low, at the base of a tropical wave, and is embedded within the ITCZ at the moment.

CATL SATELLITE LOOP

Upper level winds are currently marginal for development, however based on the current wind shear forecast, upper level winds are forecast to become more conducive in 24 hours.

I will continue to monitor this area during the next 48 hours for any significant changes…albeit dry air may be an inhibiting factor.

Elsewhere, it appears our lull may be coming to and end…SOON!  Analysis of Global Models this morning is still nothing to write home about, however, the GFS does indicate an upswing in tropical activity around the Cape Verde islands at months end, indicating two tropical systems back to back around that time.  It appears we may have what is called a “back weighted” season, where we get the majority of activity in September, and October.  In some previous “analog” years I’ve been looking at, seasons of this type have averaged between 9 and 10 storms…8-9 hurricanes from the beginning of September, until the end of October.

Do I believe this may occur? Yes…still based on a couple of forecast parameters, and what we have seen so far this season.  The NAO is still forecast to head toward negative, and may remain near a weak negative to neutral state.  This would allow for warm air to pile up in the MDR due to slower trade winds, and allow for less evaporation to occur from the sea surface.  Although evaporation is needed to allow water vapor to rise and form clouds, too much wind in the tropics has the opposite, or cooling effect not allowing for latent heat to rise, and allowing the sea surface to become cooler.  This is one reason we have had less instability over the Tropical Atlantic…the NAO is the pressure difference or measurement if you will, between the Icelandic Low and Azores / Bermuda High.  When the Icelandic Low is deeper (stronger), and the Azores High is stronger than the mean average, we have what is considered a POSITIVE NAO phase.  This creates or helps to create the conditions I just mentioned above, not to mention, helps reinforce the SAL coming off Africa.  Even without the SAL, a stronger high pressure cell will produce drier conditions in the atmosphere, the familiar dry air we see in satellite imagery, minus any SAL outbreaks.  When both of these features are weaker than the mean average, the NAO becomes a NEGATIVE phase.

The current forecast is for the NAO to dip toward the negative.

The updated forecast to the MJO indicates a moderate to strong upward motion phase in about 4-5 days, and remaining for approximately 2 weeks.  This may increase activity quite a bit, as generally, this time of the season doesn’t rely on the MJO for development in the MDR.  Again, Global Dynamic models for the MJO Multivariate Index share the consensus of the MJO returning to phases 8 and 1 within the next few days.  Two of the major models, GFS and ECMWF have been in agreement on this for the past few days.

NAO PAST OBSERVATION AND FORECAST

00zecmwfensnao

MJO OLR FORECAST

So, looks like I may have my work cut out for me very soon.

Given climatology of some of the analogs, and lack of any hurricanes or major hurricanes thus far, I usually do not make adjustments, however I am lowering my forecast for the season to a more “realistic” possibility.  The first set is my original forecast:

JUNE 01 SEASONAL FORECAST

Total storms: 16-18
Hurricanes:  9-10
Intense Hurricanes: 5-6

NEW FORECAST

Total storms: 16-18
Hurricanes: 8-9
Intense Hurricanes: 3-4

Have a blessed day!

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST
MEMBER WEST CENTRAL FL AMS
CERTIFIED SKYWARN OFFICIAL STORM SPOTTER (advanced)
CoCoRaHS OBSERVER

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About palmharborforecastcenter

I am a Tropical Forecast meteorologist, providing hurricane forecasts during the Atlantic Hurricane Season. I retired from the U.S. Coast Guard in July of 2001. Meteorology became my passion in high school, and I have continued my educational background in meteorology since 1996, when I undertook the study of Tropical Meteorology. While working toward my degree, I had to unexpectedly withdraw from college due to my oldest sons medical reasons. I do however, meet the educational criteria of the AMS to be recognized as a meteorologist. Studies include, but are not limited to the Navy Aerographers Mate course, Naval METOC meteorology course, Meteorology 2010 Sophomore level course while attending St. Petersburg College, Clearwater, FL., Basic Forecasting course for operational meteorologists from Rapid WX, meteorology institute, a four month meteorological internship, and extensive research on numerous meteorological topics such as the MJO, NAO, satellite imagery interpretation, etc. I have been forecasting Tropical Weather (Tropical Storms and Hurricanes) since 1996, with my main client being three different Coast Guard Commands.
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10 Responses to TROPICAL WEATHER FORECAST SYNOPSIS…AUG. 20, 2013…ISSUED 11:30 A.M. EDT…PHFC

  1. Monty says:

    Thanks Storm. I echo all…REST UP SENIOR CHIEF!!

  2. Elliot Lisak says:

    Good Day Sr. Chief

    Thank You for your insight. However, if I may I really don’t see any major difference between
    the June Prediction and now except for the Intense category. And with the fact that the systems that have formed prior hasn’t really utilized much in warm water & energy in their creation. Therefore we might get more in intensity, size, moisture etc even though the numbers might be down. I have gone thru tropical storms and they get to provide more than enough problems without them being designated a Hurricane or Intense Hurricane

    Therefore, I’ll give my usual synopsis, in the end it only takes one to ruin your day (our day). It only takes one to destroy your lives work, your home, personal belongings and may be your life.

    So I’m not going to prepare any less for the difference +/- 1 or 2. If people are smart they always
    prepare not just for the Tropical Storms, Hurricanes, Flood, Wildfire, Earthquake or for that matter a Terroist Attack.

    The WC had a comment in this mornings piece but the bottom line for people, as it always is no matter what is going on: don’t become complacent.
    JUNE 01 SEASONAL FORECAST

    Total storms: 16-18
    Hurricanes: 9-10
    Intense Hurricanes: 5-6

    NEW FORECAST

    Total storms: 16-18
    Hurricanes: 8-9
    Intense Hurricanes: 3-4

    Thanks again Chief because your the lifesaver that we should always keep close. Stock up on caffeine. Here we go!

  3. stefanie says:

    Thanks Storm. My numbers are 14/4/1. Lol. As if that makes any difference. Have a good day. 🙂

  4. dellamom says:

    Okay, I vote for forecast 2 (unless you have one with NO intense hurricanes, then I’ll take that one). Seriously, thanks for keeping on top of this for us and for all you do. God bless (and get some rest ’cause you’re obviously gonna need it).

  5. originallt says:

    Thanks Storm for your latest up-date. If what you say comes true, you really will be busy come Sept. into Oct. I know you will be ready.

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